diff options
| author | Willy Tarreau <w@1wt.eu> | 2008-02-09 17:24:08 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2008-02-09 17:24:08 -0500 |
| commit | 36445cf30686b9ea4ddf71f28057e4dd07db0e2d (patch) | |
| tree | 8859c7d06e98b0c7ed03fbb934a0d40f69ad875d /arch/x86 | |
| parent | e78a77c38cf0ce3b8169ff6a6fd3711e81dc22c8 (diff) | |
x86: GEODE fix MFGPT input clock value
The GEODE MFGPT code assumed that 32kHz was 32000 Hz while the boards
run on a 32.768 kHz digital watch crystal. In practise, it will not
change the timer's frequency as the skew was only 2.4%, but it
should provide more accurate intervals.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andres Salomon <dilinger@debian.org>
Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/mfgpt_32.c | 27 |
1 files changed, 13 insertions, 14 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c index 9146b2de1698..586228140b9e 100644 --- a/arch/x86/kernel/mfgpt_32.c +++ b/arch/x86/kernel/mfgpt_32.c | |||
| @@ -12,21 +12,20 @@ | |||
| 12 | */ | 12 | */ |
| 13 | 13 | ||
| 14 | /* | 14 | /* |
| 15 | * We are using the 32Khz input clock - its the only one that has the | 15 | * We are using the 32.768kHz input clock - it's the only one that has the |
| 16 | * ranges we find desirable. The following table lists the suitable | 16 | * ranges we find desirable. The following table lists the suitable |
| 17 | * divisors and the associated hz, minimum interval | 17 | * divisors and the associated Hz, minimum interval and the maximum interval: |
| 18 | * and the maximum interval: | ||
| 19 | * | 18 | * |
| 20 | * Divisor Hz Min Delta (S) Max Delta (S) | 19 | * Divisor Hz Min Delta (s) Max Delta (s) |
| 21 | * 1 32000 .0005 2.048 | 20 | * 1 32768 .00048828125 2.000 |
| 22 | * 2 16000 .001 4.096 | 21 | * 2 16384 .0009765625 4.000 |
| 23 | * 4 8000 .002 8.192 | 22 | * 4 8192 .001953125 8.000 |
| 24 | * 8 4000 .004 16.384 | 23 | * 8 4096 .00390625 16.000 |
| 25 | * 16 2000 .008 32.768 | 24 | * 16 2048 .0078125 32.000 |
| 26 | * 32 1000 .016 65.536 | 25 | * 32 1024 .015625 64.000 |
| 27 | * 64 500 .032 131.072 | 26 | * 64 512 .03125 128.000 |
| 28 | * 128 250 .064 262.144 | 27 | * 128 256 .0625 256.000 |
| 29 | * 256 125 .128 524.288 | 28 | * 256 128 .125 512.000 |
| 30 | */ | 29 | */ |
| 31 | 30 | ||
| 32 | #include <linux/kernel.h> | 31 | #include <linux/kernel.h> |
| @@ -45,7 +44,7 @@ static struct mfgpt_timer_t { | |||
| 45 | 44 | ||
| 46 | #define MFGPT_DIVISOR 16 | 45 | #define MFGPT_DIVISOR 16 |
| 47 | #define MFGPT_SCALE 4 /* divisor = 2^(scale) */ | 46 | #define MFGPT_SCALE 4 /* divisor = 2^(scale) */ |
| 48 | #define MFGPT_HZ (32000 / MFGPT_DIVISOR) | 47 | #define MFGPT_HZ (32768 / MFGPT_DIVISOR) |
| 49 | #define MFGPT_PERIODIC (MFGPT_HZ / HZ) | 48 | #define MFGPT_PERIODIC (MFGPT_HZ / HZ) |
| 50 | 49 | ||
| 51 | #ifdef CONFIG_GEODE_MFGPT_TIMER | 50 | #ifdef CONFIG_GEODE_MFGPT_TIMER |